Facebook has begun allowing users to upload a seven-second video instead of a plain old profile picture.

The social network is now offering selected users the ability to upload looping GIF files using their iPhone, with desktop users told the feature is "coming soon".

The tech giant tends to roll out new apps and functionality in small bursts, testing it on a group of people before unleashing it on the rest of the world.

It is currently testing the feature with a few favoured Facebookers, who are already posting videos of themselves instead of photos.

Some users have been requesting the moving profile pics for years, meaning many will new the new feature as a GIF which will keep on giffing (the word used to describe the act of making a looping video).

But other users are likely to be confused by them.

We're testing a new site:This content is coming soon

How do you post a GIF to Facebook?

All you have to do is paste the link to the GIF of your choice into your status update bar - and hit post!

Just make sure the link you're pasting ends in '.gif', like this one: http://i.giphy.com/45IWaHPrkp9v2.gif.

If you haven't yet been given the ability to upload videos, you can still put gif files in your chum's timeline.

Just copy the address above to have a go yourself.

You can find GIFs on the internet by searching on Google images, on Tumblr or sites like Giphy and Imgur.

If yours doesn't work yet, then just hold tight, as it should be generally available soon.